臺灣博碩士論文加值系統

本文詳細探討時間延遲效應對直接輸出回饋控制系統穩定性的影響。首先
從控制後系統極點以及模態特性，探討在具時間延遲下最佳直接輸出回饋
控制系統之穩定性，推導會使直接輸出回饋控制無效以及系統不穩定之延
遲時間 $($稱臨界延遲時間和最大延遲時間$)$ 的解析解，結果發現直接
速度回饋比狀態回饋容許較長的延遲時間，選擇適當的控制力加權因子或
增加結構高模態阻尼將使得最大延遲時間不再由最高模態控制，如此將使
系統的臨界延遲時間和最大延遲時間增長數倍之多，可大大地增進控制系
統之穩定性。最後，本文建議一主動結構控制的設計流程。

In this study, the stability of direct output feedback control
systems is investigated in the analysis of system poles and
modal properties after the application of control forces.
Explicit formula are obtained analytically to determine the
maximum delay time, td_max , for system instability, and
critical delay time, td_cr, for control ineffectiveness, for
state feedback and direct velocity feedback control systems,
respectively.These two quantities can be used as criteria for
active control design and the need of solutions to time delay
problem. It is found that direct velocity feedback has longer
td_max and td_cr than state feedback.td_max and td_cr decrease
with the increase of structural original natural frequency as
well as active damping due to active control. This study
develops a formula to calculate the minimum control force
weighting factor which makes the system stability dominated by
lower modes. Hence, the maximum delay time and critical time
can be dramatically lengthened by appropriate selection of
control force weighting factor and increase of higher
modal damping. Finally, an optimum design procedure for
direct output feedback control of structures is proposed.

In this study, the stability of direct output feedback control
systems is investigated in the analysis of system poles and
modal properties after the application of control forces.
Explicit formula are obtained analytically to determine the
maximum delay time, td_max , for system instability, and
critical delay time, td_cr, for control ineffectiveness, for
state feedback and direct velocity feedback control systems,
respectively.These two quantities can be used as criteria for
active control design and the need of solutions to time delay
problem. It is found that direct velocity feedback has longer
td_max and td_cr than state feedback.td_max and td_cr decrease
with the increase of structural original natural frequency as
well as active damping due to active control. This study
develops a formula to calculate the minimum control force
weighting factor which makes the system stability dominated by
lower modes. Hence, the maximum delay time and critical time
can be dramatically lengthened by appropriate selection of
control force weighting factor and increase of higher
modal damping. Finally, an optimum design procedure for
direct output feedback control of structures is proposed.